Presentation on theme: "Biogeography and Evolution Leith Nye and Rachel Schmidt February 28, 2006."— Presentation transcript:
Biogeography and Evolution Leith Nye and Rachel Schmidt February 28, 2006
Biogeography “ the study of what organisms live where on earth and why” (from Humphries and Parenti, 1999)
A naturalist in Europe… Carolus Linnaeus (1707–1778)
From the Ark to Ararat Bible (AD): Young Earth Single creation of perfect species Origin: Mt. Ararat, Turkey where Ark landed Linnaeus (1735): Notes variation in form Mountainous island center of origin theory Possible remains of Noah’s Ark, Mt. Ararat Linnaeus’s Mountainous Island Post Flood
Buffon the Visionary Georges Buffon (1761) Noted faunistic differences and similarities between regions of similar climate (“Buffon’s Law”) Fossils, extinction, changes in species, climate and geography Map of Artic from Histoire Naturelle Georges de Buffon ca. 1760
Continuing Exploration Humboldt (1805) Plant zonation, associations and biomes Candolle (1820) Coined term ‘endemic’ Defined ca. 20 regions of endemism Disjunctions: bipolar and Africa-Austraila Augustin Pyrame de Candolle Alexander von Humboldt
Geographical regions have characteristic biotas. Similar/closely related taxa tend to be closer together than more distantly related groups. Similar environments are found in different areas BUT the same species may not be found in all places where they could be! Not closely related species in similar environments may appear similar due to convergence. What are patterns of distribution of species seen across the globe?
How else might we explain this distribution without biogeography principles?? What distributions would we expect to see WITHOUT macroevolution??
What broad distribution patterns do we actually see?
Distinct Faunas across Similar Environments Wallace’s Faunal Regions
Distinct Floras across Similar Environments Good’s Floristic Regions
“In considering the distribution of organic beings over the face of the globe, the first great fact that strikes us is, that neither the similarity nor the dissimilarity of the inhabitants of various regions can be wholly accounted for by climatal and other physical conditions.” Charles Darwin, The Origin of Species A reasonable nonevolutionary prediction is that species should occur wherever their habitat is. However, macroevolution predicts just the opposite — there should be many locations where a given species would thrive yet is not found there, due to geographical barriers. Futuyma, D. (1998) Evolutionary Biology. Third edition. Sunderland, Mass., Sinauer Associates
The Origin of Species Evidence: Geographical Distribution I and II 1.Regions with identical climate have different floras and faunas (Buffon’s Law). 2.Geographic barriers closely associated with breaks between taxonomic groups. 3.Within a region, organisms are often closely related even across environmental gradients and lower taxonomic groups often show narrower distributions than higher.
1. Similar Climate, Different Taxa Cactaceae in North American deserts Courtesy of K.J. Sytsma Euphorbiaceae in southern African deserts
Geographic Barriers and Distinct Biota Very different marine biota More similar marine biota
3. Closely Related Taxa in Close Proximity Wallace’s Line
Disjunctions: A Bur in Darwin’s Saddle Darwin goes to great pains to show how disjunct patterns of species distributions can be explained through climate changes, geological changes and dispersal. Examples: 1.Same alpine species on mountains between and across continents result of cycles of glaciation and migration. 2.Similarity of freshwater fish species across continents due to flooding, twisters, birds, salt water tolerance etc. 3.Islands biota can be explained by dispersal and previous existence of now submerged island chains.
Courtesy of K.J. Sytsma
Islands- Hawaii vs. Madagascar “He who admits the doctrine of creation of each separate species, will have to admit that a sufficient number of the best adapted plants and animals were not created for oceanic islands, for man has unintentionally stocked them far more fully and perfectly than did nature.” -Darwin, The Origin of Species Courtesy of K.J. Sytsma
Vicariance Theory Lacking Mechanism “Other authors have thus hypothetically bridged over every ocean and united almost every island with some mainland. If indeed the arguments used by Forbes are to be trusted, it must be admitted that scarcely a single island exists which has not recently been united to some continent. This view cuts the Gordian knot of the dispersal of the same species to the most distant points, and removes many a difficulty; but to the best of my judgement we are not authorized in admitting such enormous geographical changes within the period of existing species.” Darwin, 1859 Courtesy of K.J. Sytsma
Plate Tectonics…Enter Alfred Wegener Wegener relied heavily on biogeographical evidence for defending his controversial continental drift theory Glossopteris Permian – “fern” Mesosaurus – Freshwater Permian Reptile Cynognathus – Triassic land reptile Lystrosaurus – Triassic land reptile Courtesy of K.J. Sytsma
Three major patterns of dispersal/vicariance modality can be identified: 1) Cretaceous dispersal to Madagascar with ensuing distributions from India (and/or South Africa) across Antarctica to South America and Australo-E. Malesia during the time of the initial radiation of the angiosperms; 2) Eocene-Oligocene (and continuing to the present) dispersal to Madagascar (and Africa) from Laurasia and W. Malesia via India (pre- and post-collision with Asia) along "Lemurian Stepping-stones" in the western Indian Ocean; and 3) continuous (and recent) long distance dispersal (LDD) to Madagascar as a function of the prevailing easterly winds and Indian Ocean currents. -G.E. Schatz, Malagasy/Indo-australomalesian Phytogeographic Connections
Species and Areas: History of Ideas 1. Acceptance of plate tectonics Up until the 1960s, most persons considered the earth's crust to be fixed. Finally, in the 1960s the geological evidence was at hand that made continental drift irrefutable. Two important scientific advances in the mid 20th century have revolutionized historical biogeography 2. Development of new phylogenetic methods Willi Hennig (1950) introduced the modern concepts of phylogenetic theory (first published in 1956). Using this methodology, hypotheses of historical lineages of species could be reconstructed. Courtesy of K.J. Sytsma
What is the ID/creationist response to biogeography?
“We see in these facts some deep organic bond, throughout space and time, over the same areas of land and water, independently of physical conditions. The naturalist must be dull who is not led to inquire what that bond is... The bond is simple inheritance.” Darwin, The Origin of Species
References: Cox, B.C. and P.D. Moore Biogeography: An Ecological and Evolutionary Approach. Blackwell Publishing, Malden, MA, USA. Darwin, C The Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. John Murray, London, UK. Humphries, C.J. and L.R. Parenti Cladistic Biogeography: Interpreting Patterns of Plant and Animal Distributions. Oxford University Press, Oxford, UK. Johnson, W.E. et al The late Miocene radiation of modern Felidae: A genetic assessment. Science 311: Knox, E.B. and J.D. Palmer Chloroplast DNA variation and the recent radiation of the giant senecios (Asteraceae) on tall mountains of eastern Africa. Proc. Natl. Acad. Sci. 92: Lomolino, M.V., D.F. Sax and J.H. Brown, editors Foundations in Biogeography. The Unversity of Chicago Press, Chicago, IL, USA. Wegener, A Die Enstehung der Kontinente und Ozeane. Sammlung Vieweg und Sohn, Braunschweig. Whitfield,J Biogeography: Is everything everywhere? Science 310: International Institute for Aerospace Survey and Earth Sciences, Gondwana Animation: